📐algorithm-longest_palindromic_subsequence-tests

The groupant beside algorithms/src/longest_palindromic_subsequence/tests.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.

Facts

Components

Obernants

The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.

Model text

descriptant

Combiner and epoch memory

2026-10-30: Original std-only implementation and independent oracle. The combiner jointly relates raw Rust, source-bound partial syntax, forward target, ordered typed obernants, invariant, cost and measured assertions. Tests and implementation remain separate leaves; passing leaves do not certify integration wiring. Direct interval dynamic programming formulation of longest palindromic subsequence; independently written recurrence, not a call to longest common subsequence. No external implementation imported.

Prospective prediction: deterministic exhaustive agreement, boundary correctness and a compiled semantic mutant rejected. Initial scope deliberately excludes throughput and downstream language quality. Preserve observations when later epochs revise these models. Full semantic AST, macro expansion, executable approximate substitutes and universal proof remain absent.

model

longest_palindromic_subsequence tests.rs model

Forward

Run two test functions for longest_palindromic_subsequence: independent exhaustive oracle and explicit boundary/relational fixtures. Pass iff all assertions hold.

Invariant

Fixture enumeration is deterministic, oracle observations are compared to production outputs, and tests use no random or external state.

Cost

Exhaustive finite verification; exponential oracle work deliberately bounded by fixture lengths. No production throughput conclusions.

nonbehavior

Type: behavior_complement. Domain: Deterministic successful Rust test runs on named bounded fixtures; no claims for unexecuted cases.

Within deterministic terminating test executions, a pass is excluded when any executed assertion is false; failure is excluded when all assertions hold. Untested inputs are outside this observation.

compatible_antecedents

Type: reverse_reconstruction. Domain: Deterministic successful Rust test runs on named bounded fixtures; no claims for unexecuted cases.

A pass admits every implementation agreeing with all tested observations; many disagree elsewhere. A failure trace restricts compatible executions to those violating its named assertion and cannot identify a unique source bug.

oracle_independence

Type: oracle_relation. Domain: Deterministic successful Rust test runs on named bounded fixtures; no claims for unexecuted cases.

Enumerate every index subset and test its reversal, without interval recurrence.

finite_scope

Type: evidence_boundary. Domain: Deterministic successful Rust test runs on named bounded fixtures; no claims for unexecuted cases.

9841 ternary words through length 8, every index subset; generic strings, constant length 1000, endpoint wrapping and projection collisions.

mutant_discrimination

Type: negative_control. Domain: Deterministic successful Rust test runs on named bounded fixtures; no claims for unexecuted cases.

A separately compiled semantic source mutant must fail a real production assertion; a compiler error does not count. This demonstrates one detected error, not mutation completeness.

Limits and reference

Direct interval dynamic programming formulation of longest palindromic subsequence; independently written recurrence, not a call to longest common subsequence. No external implementation imported. Finite evidence is not a proof; partial syntax omits macro expansion and semantic resolution. No executable approximation profile is declared for these exact routines.

evidence

Evidence 2026-10-30

Passed: two debug and two release executions of the 220-test library, including two new tests for this algorithm. Ordered successful test records are byte-identical across all four runs after removing timing and harness-order noise. Strict cargo clippy -p mova-algorithms --offline --all-targets -- -D warnings and rustfmt --check on all six owned Rust files pass. One initial Clippy finding in the Huffman oracle was corrected to isolate_lowest_one before the final four-run verification.

Scope: 9,841 ternary sequences through length 8 against exhaustive index-subset palindrome enumeration, with reversal checks. Explicit empty, singleton, equal/distinct pairs, known examples, generic &str symbols, length-1,000 constant input, wrapping and scalar collisions.

Negative control: Changing equal-endpoint diagonal + 2 to diagonal + 1 in a separate copy compiles with rustc --edition 2024 --test; tests::boundaries_generic_and_loss rejects it with an assertion failure and exit 101. The production source is unchanged by mutation checks. Compile failure does not count as rejection.

Both Rust files have syntax projections generated twice by installed mova-modelcheck syntax and compared byte-for-byte; manifests bind exact source SHA-256. No macro expansion or semantic resolution is claimed. Logs, normalized records and Rust gate helper are under $MOVA_DATA/runs/octopus-wave5-strings-2026-10-30. Temporary lib.rs exports were used for local checks and restored before commit; parent registry/wiring validation belongs to integration.

Finite evidence is not a universal proof or throughput measurement. Exact routines have no approximate executable profile, and no downstream school gain is claimed.

prospective

Prediction recorded before final gates

2026-10-30. Predict longest_palindromic_subsequence agrees with its independent oracle over the bounded domain; debug/release result records repeat exactly. Predict semantic mutant fails a real assertion. Cost prediction: Exactly n(n-1)/2 endpoint equality evaluations; O(n²) word operations and O(n) words. Equality cost is additional. Result at most n so additions fit usize for allocatable input.

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